The present invention relates generally to hydromechanical transmissions and, more specifically, to hydromechanical transmissions of the type utilized to provide a constant speed output from a variable speed input. Typically, transmissions of this type are utilized in aircraft with the aircraft engine driving the transmission at a variable input speed. The input power is transmitted both hydraulically and mechanically through the transmission with the outputs of the hydraulic and mechanical sections of the transmission being summed to drive an output shaft at a constant speed. A generator is connected to the output shaft and thus also is driven at a constant speed so as to produce a constant frequency source of electrical power for the various accessories of the aircraft.
Transmissions of the foregoing general character are disclosed in U.S. Pat. Nos. 3,365,981 and 3,733,924. Another, possibly relevant transmission, although not of the constant speed output type, is disclosed in U.S. Pat. No. 3,489,036.